T, C, M and H waves in the masseter muscles were induced by mechanical, transcranial magnetic and peripheral electric stimulation in 24 healthy, 2 TMD and 1 cerebral infarction volunteers. The mean (1S.D.) latency, duration, amplitude and area values from healthy ones were 7.35(0.61)ms, 8.55(1.39)ms, 0.21(0.09)mV and 0.37(0.20)mVms to the T waves at rest, 9.87(1.63)ms, 23.3(3.11)ms, 0.09(0.05)mV and 0.44(0.24)mVms to the C waves at rest, 7.88(1.23)ms, 29.4(3.60)ms, 0.25(0.17)mV and 1.26(0.91)mVms to the C waves during jaw opening, respectively. Ipsilateral C waves were also induced during jaw opening and clenching. Two responses induced by peripheral electrical stimulation were revealed masseteric M and H waves by their latencies, induced patterns and high frequent double shock tests. Bilateral silent periods after electric or magnetic stimulation were also investigated by electro-magnetic or magneto-electric double shock tests. The former suppressed C waves bilaterally, while the latter did not suppress H waves. So, the silent period induced by the conditioning stimulus might be partly caused by different origins such as inhibitory cutaneous input or disfacilitation of the motoneurons besides refractory period after M or C waves. Suppression of bilateral T waves by mechano-magnetical stimulation at the same time might be caused by augmentation of the muscle tones due to induced M wave or by the following refractory period or by inhibitory input from the cortex. Two unilateral TMD patients who had normal M and H, small T and delayed C waves in the impared side might have less sensitivity of muscle spindles and some of conduction block. Ipsilateral cortico-motoneuronal compensation in a infarction case was suggested because the stimulation of the intact brain side could evoke C waves in the first dorsal interosseus muscles bilaterally, although weaker stimuli could evoke C waves in the peripheral paretic side only.